For crowd control, it is known to link together simple spaced so-called A-frames with horizontal rails; the frames, of course, are not free-standing and they are easily jarred loose. Thus, especially for police use, free-standing metal-type grids which interlock are commonly used. These are, of course, relatively cumbersome and expensive. In the highway field as illustrated by U.S. Pat. No. 5,003,912, barricades of molded plastic have been known for some time. They typically includes two frame or panel units hinged together so they can be spread apart for use. The individual panel units are one-piece, integral, hollow plastic panels formed by rotational or blow molding. For increased stability, the hollow plastic panels may be filled with sand as a ballast. To provide for crowd control, it would be desirable to link these barricades together in a manner in which an interlinking rail is not easily jarred loose.